A transmission electron microscopy study of polymer-stabilised liquid crystal structure

A method has been established for observing the internal structure of the n etwork component of polymer-stabilised liquid crystals. In situ photopolyme risation of a mesogenic diacrylate monomer using ultraviolet light leads to a sparse network (similar to1 wt%) within a nematic host. Following polyme risation, the host was removed through dissolution in heptane, revealing th e network. In order to observe a cross-section through the network, it was embedded in a resin and then sectioned using an ultramicrotome. However, im aging of the network was not possible due to poor contrast. To improve this , several reagents were used for network staining, but only one was success ful: bromine. The use of a Melinex-resin composite for sectioning was also found to be advantageous. Imaging of the network using transmission electro n microscopy revealed solid "droplets" of width 0.07-0.20 mum, possessing a n open, yet homogeneous structure, with no evidence for any large-scale int ernal structures. (C) 2001 Kluwer Academic Publishers.